1. Field of the Invention
The present invention generally relates to a semiconductor process, and more specifically to a semiconductor process that enlarges the temperature gradient of a wafer to improve a metal silicide quality formed in the wafer.
2. Description of the Prior Art
A metal silicide is often used on contact surfaces between silicon (substrate/gates) and metal (wires/contact plugs). The metal silicide not only can reduce the contact resistance or the gate resistance to improve the driving current, the reactive time or the operation speed of the formed semiconductor component, but also can be formed through a self-alignment process. In general, the salicide (self-aligned silicide) process is performed after gates, and spacers, source/drains formed beside the gates are formed, and the salicide process is performed to form the metal silicide on silicon substrate/gates directly without further performing lithography processes to the silicon substrate/gates by the structural features itself. For example, when the metal films for forming the metal silicide are deposited on the silicon substrate/gates and the annealing processes are performed, the metal on the silicon surfaces of source/drains and gates of MOS transistors will be transformed into metal silicide, but other parts such as isolation areas or spacers won't have metal silicide formed thereon, and can therefore be removed through selective wet etching processes.
As the semiconductor processes are developing and the semiconductor components size continually reduces, salicide processes should be improved accordingly.